The appearance of the great ran538jq * q9gwshae:ow-d-dmi lge of brightness among stars is due to

  The absolute luminosity for most stars depzb 4uc/(e ul( jfol:;zipn0 5oends on the

  Four different main-sequence stars are wp n:km5qbogy:b - k05colored blue, orange, red, and yellow. What is their rank5k0 by:wbg-nmo:qk5p from coolest to hottest?

  A Hertzsprung-Russell diagram shows stai/xk a54 9 gjr7zqpto1rs on a plot of

  A white dwarf star with a mas:ugoujyda.h*ch-o2 fr1ki (.u8 gz l*s equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapsesurllj:qx:dr0v 3caj3 )e ieyq 1 0f(, into a white dwarf) is,,x 001vrsl(: d : uraljfjcy3e)i3qq e if the mass of our Sun is M, about

  Supernovas are thought to always resulnkaj5aajt1mc 644kbkh 8e ; 5lt in

  Black holes

  Pulsars are rapidly spinningw,tfbe,7o *.hct4,) evtsh bb

State Einstein's principle oht 0ver.hi3 sodzh+ju;1 5dhm) rqm+*f equivalence.

  The Schwarzschild radius of a black hole is that radial distance from theiq n*jt mc-5;3l4 2yzaiv o 4jqx(uf9e center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published his general relativity theory. It can be calculao5 q-lnxft3u 4 v;*qci42 j9jyma(iezted from a star's mass M as: $R = 2GM/c^2$. Take the radius of both stars A and B as the Schwarzschild radius. If the mass of star A is twice as much as the mass of star B, the average density of star A, compared to star B will be

  When a distant source emits lijde-g: ttn5 2qght of a particular wavelength in the visible, and the source is moveq-2:nt5dgj ting away from us, the color of the light appears to us to be shifted toward the

  The cosmic background rad2-(fu2b lsc*cpvc4rts6xle1/v7 ho viation corresponds to a temperature of about

  The Sun has apparent brigp62i i hwtq5 18-hpafjhtness at Earth ($1.5 \times 10^{8} \; km$ away) of B. What would be the apparent brightness of the Sun at Pluto, which is $6.0 \times 10^{9} \; km$ from the Sun?

  A star has absolute luminosity equal to tivn5j. zc)jw,taad,6 y 3j ux:hat of the Sun ($1.5 \times 10^{8} \; km$ from the Earth) but is 10 pc away from the Earth. By what factor will it appear dimmer than the Sun?

  The Earth's orbit has a mean radiusc7 iba:*ri-dh of $1.5 \times 10^{8} \; km$. Over a six-month period, the apparent position of a particular star varies by $0.00014^{\circ}$ due to parallax. How distant is the star, in km?

  The Earth's orbit has a mean radius o/a mw. u4iq7) bpzf7umf $1.5 \times 10^{8} \; km$. Over a six-month period, the apparent position of a particular star varies by $0.00014^{\circ}$ due to parallax. How distant is the star, in ly? (1 ly = $9.46 \times 10^{15} \; m$)

  What is the parallax angle for Proxima Centauri, which is Earth's nea;*xjd9aurqb)4 aq8lkwqdjgjz u 16 e83mr; y,rest star at 4.3 lymwa)*43xad1d ;k89;8 rl jqyqqerju zgb u ,6j?

  The apparent brightness of a w4 1qy 1bvhnje+1be7 lstar is $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the a kx 0grv/gj +1b3eun4approximate age of the universe is 1/H, where H is the Hubble constant. Takin geb+k1r3navuj4 0gx /g H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of q7 c ur3vmkb6rbq*oc)c 5h -fci sxu+-+jr;z5 the speed of light, how far away is it from 7xq*q+ obs6km3- uc+rzj cvc;cb hrui)r55-f us?

  Estimate the speed of a galaxy that is 10 billion limh* nb6cjo8d1u+c q 8jght-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a star56l y)8e8gw gx gejbe; which is 1e b8w5j6g g) ;8ygeelx00 million light-years from us.

  About 1 ms after the Big Bang, the temt z(7 i j-kficq,h3k-jdj5qe)3f3 pvjperature of the universe was about 1013 K. What energy (in7f33p)jdtkjqi-3cf ekqi-j ,h5 vz( j eV) does this correspond to?